Research Regarding Improvement of Dynamic Behaviour for High-Ratio Planetary Gears

摘要

High-ratio planetary gears are frequently used in robot arm articulations for the purpose of transmitting motion from the electric motors to the moving elements. Actual planetary gears used in industrial robots have a relatively large weight related to the gear ratio, which leads to a high inertia of the moving elements. Throughout this paper, a novel computation method of the dynamic momentum is presented as well as constructive methods used to improve the dynamic behavior of the planetary gear. The optimization method regarding the dynamic behavior is based on the reduction of all moving masses towards the motor shaft but also on new construction strategies for planetary gears that help minimizing the gyration momentum. This method has been applied for a three-stage planetary gear having a gear ratio of 175.61:1 in order to optimize the shape of the carriers that are attached to the output shafts, according to its kinematic diagram. The results obtained will be presented comparatively and in a graphical form, thus serving as a practical guide addressed to the designers or manufacturers of industrial robots.